The continuous sounds of a heat pump fan operating without stopping throughout the night can be very irritating to a person. The nuisance of the fan is often combined with the fact that the heat pump system are not functioning correct. A fan that does not shut off wastes electricity and puts strain on the heat pump motors.
Furthermore, the fan that does not shut off is often an indication of additional issues with the heat pump system that may cause the homes to be without heat when the individuals in the home need heat the most. Homeowners may think that the heat pump system is performing its normal function, yet the fan running continuously indicate an issue with the system. Manufacturers often design heat pumps to cycle on and off with the individual need of the home for heating or cooling, as well as for the defrosting of the system.
These cycles can often be a cause of the heat pump system to develop additional issues that compound the initial problem. Knowing the causes of the heat pump fan running will allow the homeowner to determine whether the issue can be fixed themself, or if they should call in a professional to repair the heat pump system. Somany different issues can be in the cause of the heat pump fan running continuously.
These causes can be ranked according to how easy it is for the homeowner to fix the issue themself, to the causes that require the expertise of a professional repair technician. Each cause of the fan continuously running has specific symptom and solutions that is worth knowing before attempting to fix the heat pump system themself. One of the first causes of the heat pump fan refusing to stop running is the result of a dirty air filter.
Common Reasons Your Heat Pump Fan Won’t Stop
1. Dirty Air Filter
If the air filter is become clogged with debris, the heat pump system will continuously run the fan to compensate for the decrease in air that passes over the evaporator coil of the heat pump. The intent of this is to prevent the evaporator coil from experiencing freezing; however, this also results in the fan not receiving the signal to shut off. Replacing or cleaning the air filter will resolve the issue with the fan in a few minutes.
We recommend homeowners to check the air filter each month during the heating season, and to replace the air filter at least every three months. If the fan begins to quiet after this step, the homeowner has found the cause of the issue: the dirty air filter. Another common cause of heat pump fans that will not stop running are the issues with the thermostat of the heat pump system.
2. Thermostat Malfunction
If the thermostat is malfunctioning, the fan will receive a constant supply of power. Issues with thermostats are common with older model thermostats and thermostats that are placed in areas of the home that experience significant temperature change. To test for the thermostat as the cause of the fan issues, the user can turn the thermostat to the off position.
If the fan stops running, the thermostat is the cause of the issues with the heat pump system. Upgrading to a smart thermostat that learns the homes temperature and humidity levels can help to avoid this issue. As the “brain” of the heat pump system, if the thermostat is failing the heat pump system will experience the consequences of that failure.
3. Stuck Relay Switch
An electrical issue with the heat pump system can also be the cause of a fan that refuses to stop. The relay switch that sends the power to the motor may have “stuck” into the on position after many years of use with the heat pump system. Technicians often start and stop heat pumps very frequent throughout the year.
These components wear down over time due to the significant amount of starting and stopping of the heat pump system. Listening to the relay will emit a clicking sound when the system attempts to cycle the fan. If the clicking sound is heard yet the fan continues to run, the relay switch has failed.
The replacement of the relay switch is less costly than the replacement of the control board that regulates the heat pump. However, the replacement of the relay switch requires the use of a multimeter and the homeowner must be comfortable performing electrical task. A third cause of the fan of the heat pump system continues to run is due to low levels of refrigerant within the heat pump system.
4. Low Refrigerant Levels
With lower refrigerant levels, the heat pump system struggle to efficiently transfer the heat from the refrigerant to the indoor air. Instead, the heat pump system is forced to cycle more often in an attempt to reach the indoor temperatures that are set by the thermostat. Additionally, the outdoor refrigerant condenser units may begin to frost over time.
Only a certified technician can legally add refrigerant to the heat pump system. Adding refrigerant to a heat pump system without authorization can damage the environment (through the release of refrigerants into the atmosphere) and void the warranty of the heat pump system. A fourth cause of a heat pump fan that refuses to stop is the result of a failing capacitor.
5. Failing Capacitor
Heat pumps use the capacitor to provide the initial surge of power necessary to start the fan. Additionally, the capacitor maintains the running of the fan. If the capacitor is failing, the fan motor experience erratic running, or may not shut off.
The capacitor can fail in two main ways: the developing bulge of the top of the capacitor, or the leaking fluid from the capacitor. Capacitors are contained within a metal can near the compressor of the heat pump system. Replacing the capacitor with the proper specification of microfarads and voltage is necessary for the proper operation of the heat pump system.
If the homeowner incorrectly replaces the capacitor, the motor of the heat pump system may be damaged. However, for those with experience with electrical systems, the failure of the capacitor will be fixed within an hour. Sensor issues within the heat pump system are another cause of the heat pump fan to fail to shut off.
6. Sensor Issues
The sensors that measure the temperature within the system or the defrost sensors may register incorrect value, which then causes the fan to be continuously running. Each sensor is located in specific areas of the heat pump system, along the condenser coils, and along the condenser wiring harness. Moddern heat pumps contain many sensor that work in conjunction with one another.
If one sensor is out of alignment, the heat pump system will enter into safe yet inefficient mode of operation. To realign the sensors or to replace any that are found to be malfunctioning will restore the efficiency of the heat pump system. Wiring issues are common in heat pump systems of many years of age.
7. Wiring Problems
Rodents have often chewed at the wires that control the fans in outdoor condenser units. Additionally, the wiring that connects the thermostat to the air handler may become loose over time. Tracing the wiring from the thermostat to the air handler will reveal the chewed wiring or loosed connection.
These sections of wiring can be replaced to restore the efficiency to the heat pump system. This fix requires the patience of the homeowner to find the correct wiring connections. The blower motor itself is another component of the heat pump system that may be developing the issue.
8. Blower Motor Failure
The bearings within the motor may be worn down and create drag on the motor, which prevents the motor from stopping. Additionally, if the motor is set to trip safety limits due to high amperage load, the fan will continue to run. Replacing the blower motor is a significant financial investment for the home owner.
However, it is still cheaper than purchasing a new heat pump system. Technicians will test the motor and the capacitor that relates to the motor prior to replacing the blower motor. Testing the motor will reveal if the motor is failing due to one of the issues described earlier with the air filter or the capacitor.
9. Frozen Condenser Coils
If the condenser fan motor of the heat pump system becomes frozen, the fan will run continuously in an attempt to melt the ice that has formed on the condenser coils to prevent further damage. Additionally, frozen condenser coils are a result of the same cause as heat pumps with refrigerant levels that are too low. Homeowners should never attempt to chip at the ice that forms on condenser coils with a tool.
Instead, the homeowner can change the heat pump system to fan-only mode to melt the ice with the circulating air. Once the condenser is clear of ice, the homeowner can address the cause of the freezing of the condenser coils. If left unchecked, the condenser fans will damage the fins that allow the air to move across the condenser coils.
Heat pump system fans refusing to stop can have many cause. Each cause is layered upon each other with the lack of maintenance of the heat pump system. The fan that refuses to stop is both a symptom of the cause and a means of the heat pump system to prevent further damage.
By taking the steps to diagnose the cause of the heat pump fan’s running, the homeowner has protected their investment in the heat pump system, and restored peace and quiet to their home. The silence of the heat pump system when the fan shuts off is worth the effort that each homeowner must put into fixing the issue.
